The invention relates to machines for the production of rod-shaped commodities wherein a stream of filler of fibrous material is confined in a tubular wrapper. Typical examples of such machines are those which are used to make cigarette rods, filter rods and similar rods which can be subdivided into rod-shaped articles (such as cigarettes, cigars, cigarillos or filter rod sections) of the tobacco processing industry. The following description will deal primarily or exclusively with the making of cigarettes; however, it is to be understood that the invention can be embodied with equal or similar advantage in other types of rod making machines, especially those which are used to turn out rod-shaped smokers' products.
A cigarette rod making machine (such as a machine known as PROTOS which is produced by the assignee of the present application) comprises a wrapping mechanism wherein a continuous trimmed or equalized stream of tobacco particles is draped into a continuous web of cigarette paper or other suitable wrapping material. The web is directed toward the wrapping station by a first guide, and a second guide is provided to control the position of the so-called garniture tape (or garniture band) which is an endless belt conveyor serving to advance the web and the stream through the wrapping mechanism past a device which partially drapes the web around the stream and compacts the stream to convert it into a rod-like filler, an adhesive applicator which coats one marginal portion of the web with a suitable adhesive, a device which completes the draping of the web around the filler so that the two marginal portions of the web form the customary seam extending in parallelism with the axis of the resulting cigarette rod, and a so-called sealer which is used to influence the setting of the adhesive to thus ensure that the tubular wrapper of the cigarette rod will stand the stresses which develop during transport of the rod through a cutoff wherein the rod is subdivided into plan cigarettes of unit length or multiple unit length.
Proper positioning of both components of the cigarette rod during travel toward and through the wrapping mechanism, as well as accurate positioning of parts which cooperate in advancing the web and the stream toward the wrapping station and in treating the web and the stream in the wrapping mechanism proper is of utmost importance because defective cigarettes must be segregated from satisfactory cigarettes and even slight deviations of the characteristics of cigarettes from a prescribed norm can result in segregation of large numbers of rejects because a modern cigarette maker turns out up to and in excess of 8000 cigarettes per minute. One of the important parameters is the manner in which a film of adhesive is applied to one marginal portion of the web in the wrapping mechanism. For example, if the film of adhesive is applied too close to the free edge of the respective marginal portion of the web, a portion of the film is squeezed out of the space between the overlapping seams when the conversion of the web into a tube is completed whereby the exposed part of the adhesive film contaminates the cigarette rod and/or the adjacent parts of the wrapping mechanism and the adhesive on such parts can interfere with proper transport of next-following increments of the web and affect the diameter of the cigarette rod. Alternatively, the film of adhesive can be applied too far away from the free edge of the respective marginal portion of the web so as to affect the appearance and stability of the seam, i.e., the wrapper of the cigarette rod is likely to burst open ahead of or not later than in the cutoff.